Coupler lock



FIG. 1 is a perspective view of a coupler lock showing my new design;

FIG. 2 is front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a first side view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a top side view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines adjacent to the shade lined indicate the boundary of the claimed design and form no part of the claimed design. All other broken lines illustrate the environment and form no part of the claimed design. 

CLAIM The ornamental design for a coupler lock, as shown and described. 